The object of the research proposed is to follow in detail biophysical, neurological and behavioral changes following a sudden disturbance to a tooth. The disturbance used will be the placement of multiple fillings in the dentin. Following stabilization, heat shock and pulp exposure will be used as secondary disturbances. Cat upper canine teeth will be used. Pulp pressure, temperature, and electrical impedance will be monitored. Pulp excitability will be monitored in awake cats, using the jaw opening reflex and a simple escape response as indices; the difference between the reflex and behavioral response will be assessed as an index to central changes, and intracranial stimulation will be used to seek sites which selectively block the escape response. Results will be interpreted in relation to dental pain.